Mold flow analysis is a simulation of fill, pack, cool, and warp — not a certificate that the tool will work. OEMs who buy a colorful PDF and skip DFM still get sliders and sink. Used well, flow study ranks gate options, flags short-shot and weld-line risk, and tells you when the CAD is the problem — before steel.
This guide is for buyers: what to request, what the pictures mean, and when a study is worth the days. It does not replace T1 CMM. Related: DFM checklist, gate location, shrinkage.
What a useful study includes
| Output | Buyer question it answers |
|---|---|
| Fill / pressure | Will it short? Is the press in range? — short shot |
| Weld / meld lines | Do they sit on snaps or Class A? — weld lines |
| Air traps / vents | Burns and shorts at the last fill |
| Cooling / warp | Banana covers, out-of-round — warpage |
| Fiber orientation (GF) | Stiffness axis vs CTQ — GF nylon, PBT |
Garbage in: wrong grade viscosity, missing thickness, or a gate the shop will not cut. Lock resin and a real gate concept first.
When to pay for it
- Thin wall or long L/t — thin wall
- Multi-cavity balance — multi-cavity
- Optical / Class A where welds are reject
- GF structural parts with tight flatness
- Expensive steel (H13, hot runner, many actions) where a recut hurts
A simple open-and-shut ABS box may only need experienced DFM. Do not buy animation for a tray.
How to read the report without being a CAE engineer
- Ask for two gate options, not one pretty picture
- Ask what press tonnage and fill time the model assumes
- Ask which welds are structural vs cosmetic
- Treat warp plots as direction, not a ±0.01 mm promise
- Write the chosen gate into the tool design — mold design
Hot runner vs cold changes the model: hot vs cold. Samples still prove it: T0–T2.
What mold-flow will not fix
Undercuts still need actions or a redesign — undercuts. Ownership and IP are commercial — IP protection. A green fill plot does not mean the quote included texture and FAI.
How Deuchi uses flow study
Deuchi runs or reviews flow when the geometry or resin makes first-steel risk expensive. We would rather change wall or gate in CAD than “optimize” a bad fill with heroic pressure. Mold build; send STEP via contact.
FAQ
Is mold-flow required for every China tool?
No. Use it when recut cost or cosmetic risk is high. Simple parts need DFM more than software.
Can we use the supplier’s study only?
Yes if they share assumptions (grade, gates, temps). A screenshot with no inputs is marketing.
Does Autodesk / Moldex3D brand matter?
Less than the person setting boundary conditions. Ask who ran it and what they changed after the first run.
Will flow analysis give our piece price?
It can inform cycle and tonnage. Price still needs cavities, steel, and ops — read the quote.
Next step: Contact Deuchi with STEP and resin if you want a DFM-first read and a call on whether mold-flow is worth running before steel.